Field of the Invention
This invention relates to apparatus upon which variable weight is applied during normal use and, more particularly, to an apparatus having at least one part with different adjusting characteristics during normal use depending upon the particular applied weight.
Background Art
A very significant percentage of furniture sold commercially has an ability to be adjusted/reconfigured to accommodate users with different body types and demands. As one example, task chairs are routinely engineered so that a single design can be offered with a substantial amount of versatility in terms of how it can be adapted to size and weight of different individuals so as to optimize function and comfort level.
In a typical task chair construction, a wheeled frame supports a vertically adjustable seat. A back rest is integrated into the frame and/or seat so that it can be tilted or reclined to accommodate a user's normal movements and/or to allow inclined back positions to be comfortably maintained by the user's upper torso weight as he/she is sitting. The task chairs may be made with or without armrests. When utilized, armrests are commonly made to be at least vertically adjustable to allow comfortable support for a user that may be different depending upon the particular user's build and/or the task(s) to be performed using the chair.
Reconfigurable designs are also commonly incorporated into seating used for leisure activities. Reading chairs and sectional pieces on modular furniture commonly have such an adjusting capability.
With a single design, performance of a particular seating apparatus will be different depending upon the weight of a user. For example, a heavier individual may be able to comfortably urge a back rest towards an inclined position and comfortably maintain potentially a number of different, desired, inclined positions within a range. On the other hand, a lighter individual with the same design may have to engage in a more unnatural movement and constantly exert a pressure on the seat back to prevent it from returning to its normal upright position, generally maintained through some sort of biasing mechanism.
Similar tilt features may be integrated into the seat itself with a user's weight affecting how the mechanisms will operate.
One industry solution to the above problem is to provide manual adjusting capabilities whereby biasing forces on movable components can be changed. For example, a mechanism has been incorporated that allows a user to change a spring force on a back rest to be more compatible with that user's weight.
Tilt and tension adjustment is typically achieved by rotating a knob or pulling a lever, which loads a spring. Once the chair is optimally adjusted, the user can recline to a comfortable backward distance. However, to optimize balance, the user must iteratively lean back and adjust. This process of adjusting tension and tilt by pulling a lever or turning a knob may require many rotations or pulls depending on the weight of the previous user, resulting in potentially wasted time and imperfect adjustments.
With the multitude of different manual adjusting capabilities currently in existing furniture designs, user operation is becoming more complicated. Even a basic task chair often has multiple actuators which a user is required to manually operate to customize a chair for his/her purposes. Oftentimes, such mechanisms are confusing to users who may default to simply using a chair in its current configuration, even if not optimally configured. This problem is aggravated when persons routinely move from chair to chair during a typical work day in certain office environments in which there are group meetings, training, collaboration at different locations, sharing of resources such as at computer stations, etc. This same sharing of chairs occurs in classrooms, libraries, open plan offices, etc.
The current demand for versatility may demand integration of adjusting mechanisms on even base line furniture. To control manufacturing costs, the quality of many of these mechanisms, and potentially the overall chair, may be compromised.
The challenges of providing customizable adjusting systems, while demonstrated in the chair environment above, is not so limited. Many different apparatus use adjusting components that rely on a certain balance that may be affected by a variable weight application encountered in normal use. As but one example, desktop mechanisms are now evolving which allow a user to elevate a work surface so that he/she has the option of either sitting or standing while working on a computer or performing other routine work day tasks. Ideally, a user has the ability to raise and lower the work surface in a range, and to maintain a desired position, without having to operate any locking or adjusting mechanisms. Given that different jobs require placement of different items on the work surface, the applied weight on the work surface may vary considerably, which makes a generic design difficult to practically construct.
These problems are contended with also in different environments and with different types of equipment outside of the furniture arena. In any environment wherein components are adjustable, designers strive to design systems so that they are affordable, reliable, and user friendly. Balancing these often competing objectives remains an ongoing challenge.